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Discussion Starter · #1 ·
Is there a veterinary or pet food industry directive to use only DL-methionine and not L-methionine?
 

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DL Methionine is the only listed form in the AAFCO approved book. Are you asking because of this info?.. "Methionine is an indispensable amino acid for humans, but there is evidence that if given in excess, it can interfere with the utilization of nitrogen from dispensable amino acids."
There doesn't seem to be studies on pets in relation to this.
 

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Discussion Starter · #3 · (Edited)
I don't have access to a copy of the AAFCO Pet Food and Specialty Pet Food Labeling Guide or any other publications.

Is DL-methionine listed in the context of other amino acids (which ordinarily would not be added to petfood) or is it mentioned along with the more common ingredients?

"Methionine is an indispensable amino acid for humans, but there is evidence that if given in excess, it can interfere with the utilization of nitrogen from dispensable amino acids."

DL-methionine is not regularly given to humans. I believe it may be added to food and disguised as "artificial flavor" but I've have never once seen it on an ingredients label intended for human consumption. I have never seen it on vitamin store shelves. I did find the pure-bulk website. This is the only source I would have for the actual racemic methionine. Obviously the benefits (whatever they may be -- cost is one) are not enough to make DL-methionine desirable on the human market.

I only ever see DL-methionine listed on dry food stuffs. Protein and fat calories are typically expensive. It may be that dry foods are produced with less protein. And in order to keep costs down DL-methionine is added in minute quantities to prevent malnutrition. Outside of sawdust and a bouillon cube, this seems sort of suspect but entirely possible. Soy may not be the choice source of methionine but it is typically an ample supply.
 

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There is no directive as far as I know but methionine is an essential amino acid with multiple vital functions. Deficiency will lead to serious complications and synthetic sources are more predictable than natural sources. If a manufacturer are ready to guarantee consistency from their natural sources they will not add DL-methionine. This is one explanation. I have seen others too related to taste and acidity.
 

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Discussion Starter · #5 · (Edited)
Well what is the virtue of DL-methionine vs. L-methionine?

D-methionine is never found in nature. Why not use L-methionine?

Ordinarily the L-amino acid would be desirable. The D-amino acid would lead to unpredictability. It would be, in essence a foreign substance, a drug, if you will -- even combined with the L-amino acid.

This amino acid has no role in any metabolic process of nature. It is absurd to think that a omnivorous mammal would be able to do anything useful with it.

I do agree that petfood would be more appetizing with methionine.

And I will also concede that methionine (in any form) is an excellent cleating substance.

If animals have diets that are inappropriately balanced, ie "ash content", "alkalinity", etc.: the correction of imbalance should not be made with D-methionine. It would require far too much of this substance. In the meantime, non-problematic nutrients would be leached from the system.

I will also say that being a substance that is never found in nature that the biological system would not be able to correctly eliminate the problematic substance while retaining the non-problematic substances as organisms naturally will do. I would even go as far as to say that D-methionine may leach calcium from the bones, the time it is available for repossession would be in the (potentially) acidic excretion of the kidneys, at which point it may be freed from the methionine.
 

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Discussion Starter · #6 · (Edited)
I bought a cat food -- green peas and salmon -- very expensive. The ingredient listed methionine.

Green peas are one of the highest sources of L-methionine known. While the cat may starve, the methionine would not be an issue.

Except rather than listing DL-methionine or L-methionine or D-methionine (for that matter), they just listed methionine.

Is this not a dubious label?
 

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I bought a cat food -- green peas and salmon -- very expensive. The ingredient listed methionine.

Green peas are one of the highest sources of L-methionine known. While the cat may starve, the methionine would not be an issue.

Except rather than listing DL-methionine or L-methionine or D-methionine (for that matter), they just listed methionine.

Is this not a dubious label?
So is corn gluten meal.
I would at least question the labeling since it is listed as an independent ingredient. I don't know what AAFCO says about labeling added methionine. Dr Tim Hunt might be able to shed some light on this if he reads this thread.
 

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I would even go as far as to say that D-methionine may leach calcium from the bones
You have me interested. Could you elaborate a little more? Any research, theories or concerns inked on this?
 

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Is DL-methionine listed in the context of other amino acids (which ordinarily would not be added to petfood) or is it mentioned along with the more common ingredients?
It is listed under ingredient definitions
 

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This is what I got in reply regarding this. The person who replied to me is a nutritionist and a formulator for a big manufacturer.

"You are correct that L-amino acids need to be provided in the diet as they are metabolically active (example: for protein synthesis, etc.) This is due to the fact that the body cannot convert L into D or D into L. However, Methionine is one of 2 exceptions to this rule and it can be converted from one to the other, reason why it is added as DL-methionine to pet foods (I use the DL form as well in [nnn brand] and all the other brands I formulate for).
If some companies prefer to only use the L-form it is likely due to personal preferences (or maybe marketing?), but in my view not due to a nutritional requirement.

I do not have knowledge of d-methionine leading to calcium losses, but I will get my assistant to run a search for journal articles in the morning to see what we can find.

Hope this helps!"
 

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Discussion Starter · #11 ·
Sorry about the delay.

I do not have evidence that d-methionine can be converted into l-methionine outside of breaking the amino acid into it's constituent parts and completely reworking the sulfur into a biologically usable form.

The breakdown of methionine can be evidenced by excretion of the d-methionine and the breakdown products, hydrogen and methyl sulfides. Seeing that these are products of said efforts, it is highly unlikely any d-methionine is converted into l-methionine in the common domestic pet (known for very short digestive tracks).

Excessive l-methionine can lead to calcium deficiency in humans.
 

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Maybe you should write the NRC and ask this question. I don't see the need to scare people by posting something like this. What is your agenda?

Is this the next Boogeyman ingredient?
 

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Topic: DL-methionine v. L-methionine: please clarify

It is pure nonsense with an ulterior motive. This reminds me of Vitamin K3.

Perhaps business is slow at the fear-mongering website run by Sabine Contreras and she needs another topic to scare people with.

The next thing will be a study where rats were injected with 6,000,000 times the amount of this nutrient and seemed depressed and withdrawn.
 

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NRC for dogs and cats has some details regarding this, but most of the info from a research perspective is done on humans.. Because this AA is essential for cats, and added into many pet food where levels may not be met naturally (or in the case of heat sensitivity), IF there was an "issue" with in, I am sure it would have shown up by now...
 

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Maybe you should write the NRC and ask this question. I don't see the need to scare people by posting something like this. What is your agenda?

Is this the next Boogeyman ingredient?
Gee, isn't it a good thing you don't decide what topics can be discussed here. Lord knows the slightest criticism of or question about a dog food ingredient can't be mentioned around you or you immediately go into full attack mode.
 

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Discussion Starter · #18 ·
I would say that it is in no way intended to not "scare" people.

The first and foremost thing I want is for someone to come up with one petfood manufacturer who states it uses only L-methionine as an additive.

But if there is some directive involving the feed industry to only use DL-methionine -- well I guess that would definitively solve my problem as well.
 

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Discussion Starter · #19 · (Edited)
What is sort of freaky concept is that D-methionine could be bio-accumulated in some of the other ingredients such as eggs specifically. Egg protein has a high affinity for methionine and the forming egg does not have the same excretory capability the hen has. The metabolism of the hen would use the L-methionine and nothing would be left accept the D-methionine. The same may be true with other sources of "natural" methionine.

I think it is a broadly held belief that additives -- as well as nutritional value -- should be scrutinized when deciding whether or not to purchase food products. It is certainly not the concept to be debunked. Not only is it the right of the consumer but it is necessary for good health.

It would be especially deceptive if the supposed nutrition of the product was actually acting like an anti-vitamin.
 

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I would say that it is in no way intended to not "scare" people.

The first and foremost thing I want is for someone to come up with one petfood manufacturer who states it uses only L-methionine as an additive.

But if there is some directive involving the feed industry to only use DL-methionine -- well I guess that would definitively solve my problem as well.
What are you worried about? Why does anyone have to come up with a food?

Sounds to me like your thread is a prelude to something else, but that's just me.

I don't find any value in worrying about it.
 
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